基于矩阵分析的团体操队形变换行进路线仿真算法

目前计算机仿真技术受到体育科研和教学人员的普遍青睐.计算机仿真技术能够为体育工作者和运动员提供更加有效的、崭新的训练指导.论文通过对大型团体操队形变换路线策略的研究,提出了一种路线变换算法——最短路线优先算法.同时,针对产生的路线冲突问题,提出了一种解决冲突的方法.最后对论文提出的算法进行了仿真分析,说明能够为团体操的演练提供很好的辅助手段.     

空场采矿法转崩落采矿法过渡过程中主要结构参数确定

针对厂坝铅锌矿工程实际,在前期利用空场采矿法开采时由于众多民采空区破坏了矿柱的完整性,导致采场频频发生失稳垮塌,严重威胁采矿工作的安全,出矿形式被迫转为在覆岩下放矿,采矿损失贫化长期居高不下,因此决定转为崩落采矿法进行后期回采。但采矿方法转变存在着采场结构参数过渡的问题,为此,系统分析了崩落采矿法研究发展现状,在大间距理论的框架下,结合工程现状,通过工程估算、经验公式、理论计算和模拟试验法,最终确定了空场转崩落过渡过程中适合该矿自身的分段高度、进路间距、崩矿步距等主要结构参数取值,为厂坝铅锌矿采矿方法转变的平稳过渡提供了科学的理论依据,也为同类矿山提供了借鉴。     

An alternative approach in ceramic shell investment casting of AZ91D magnesium alloy: In situ melting technique

In this research, the possibility of ceramic shell investment casting of a magnesium alloy using in situ melting technique was explored. AZ91D granules were charged into shell investment mould and in situ melted under various processing parameters including heating temperature, flux application, shell mould thickness and permeability. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques were used to characterise the cast samples. Thermal analysis was employed to further investigate the effect of mould thickness on the solidification behaviour of the metal. It was found that mixing flux with the granules not only reduced the temperature at which melting can be achieved, but it also contributed to produce castings with acceptable surface quality. The use of thinner mould provided higher solidification rate, which is believed to favour in situ melting of the granules. It enabled melting of the granules at 650 °C, which in turn helped to suppress the mould–metal reaction and produce castings with good surface quality. Shell mould permeability showed no influence on suppressing the mould–metal reaction at 650 °C.     

大跨高墩连续刚构桥不对称悬臂段施工技术

随着我国交通事业的发展，其对桥梁的结构和性能也提出了更高的要求。本文主要分析了大跨高墩连续刚构桥不对称悬臂段施工现状和主要施工技术要点，并成功将其应用于实际，以期为同类桥型的施工提供借鉴。     

浅析大直径深孔灌注桩施工技术

随着经济的发展和施工技术的进步,国内桥梁越来越多的采用了大跨径桥梁。桥桩基础也相应采用大直径的深孔灌注桩,本文以增从高速公路的增江大桥为背景工程,对大直径深桩钻孔灌注桩施工的技术进行总结。     

Experimental investigation on flexural behavior of concrete-filled pentagonal flange beam under concentrated loading

The flexural behavior of simply supported concrete-filled pentagonal flange beams (CFPFBs) under mid-span loading is experimentally and numerically investigated. There are two CFPFB specimens tested to failure under static load condition to determine the beam flexural capacity. One of the test specimens is designed with a pair of transverse stiffener at mid-span while the other is without any stiffener to resist the load. Both the test specimens have identical geometrical and material properties. From the experimental results, the flexural capacity of the specimen with stiffener is found to be 10% higher than that of the specimen without stiffener. The failure behavior shows the importance of transverse stiffener to enhance the ultimate flexural capacity and to avoid the localized web distortion of the beam. In the numerical study based on finite element (FE) analysis, the concrete and steel materials are modeled using the eight-node solid and four-node shell element respectively. A comparison of the ultimate capacity of the CFPFBs with and without stiffener reveals that the FE models simulate very well the flexural behavior of the test specimens and the difference of maximum load is found to be less than 10%.     

液层厚度比对环形腔内双层液体的热毛细对流稳定性的影响

为了了解微重力条件下、水平温度梯度作用时,上部为固壁的环形腔内双层流体系统中液层厚度比对流动稳定性的影响,采用隐式重启Arnoldi方法(IRAM)对环形池内5cSt硅油/HT-70双层流体的热对流过程进行了线性稳定性分析,获得了不同液层厚度比下的临界Marangoni数、临界波数、临界相速度,并通过计算特征向量,得到了临界Marangoni数附近液-液界面的热流体波形态。     

谈基础大体积混凝土施工裂缝控制

从养护、振捣方式、外部环境等方面对基础大体积混凝土出现裂缝的原因进行了分析,并对防止基础大体积混凝土裂缝的措施作了研究,主要包括削弱水泥水热化作用、严格施工管理、做好混凝土养护工作等,以期保证工程的施工质量。     

Modeling tree root diameter and biomass by ground-penetrating radar

Roots play a key role in ecosystem functioning as they transfer water and nutrients from soil to plants.Traditional methods for measuring roots are labor-intensive and destructive in nature,which limits quantitative and repeatable assessments in longterm research.Ground-penetrating radar(GPR) provides a non-destructive method to measure plant roots.Based on the superiority of GPR with 2 GHz frequency,we developed a new,practical method to estimate root biomass.First,average root matter density was measured ...     

Highly efficient VLSI architecture for DWT with low-storage implementation

With the gradual increase in image resolution of the spacecraft camera, it is highly required to figure out the problem how to process a huge amount of image data on board at a high speed. As a solution, the CCSDS proposes a space-oriented image-coding standard. For the sake of high image-coding performance, it adopts wavelet transformation as a method of image data transformation. However, wavelet transformation contains multi-level data processing, which causes more computational time consumption and more memory utilization. In order to solve this problem, we propose a highly efficient VLSI architecture for DWT with low-storage. By revising the traditional lifting structure and employing time-multiplex data processing strategy to perform the second and third level of wavelet transformation by the same logic module, the usage of logic resource is reduced with no sacrifice on speed.Using a small amount of on-chip memory instead of off-chip memory to save certain parts of DWT coefficients and sending the coefficients in a specific sequence to entropy coder timely, the off-chip memory for storage of DWT coefficients is no longer required. The proposed VLSI architecture of DWT is already implemented on the Xilinx FPGA XC4VSX55, which can achieve a high performance, in terms of data throughput, reaching 95.91MPixels/s.